1. Field of the Invention
The present invention relates to a positive temperature coefficient thermistor device which is used, for example, as a heat generating device for heating compressor oil.
2. Description of the Related Art
The positive temperature coefficient thermistor device, hereinafter referred to as the PTC thermistor device, has an automatic temperature-controlling function such that resistance of the positive temperature coefficient thermistor body, hereinafter referred to as the PTC thermistor body, drastically increases upon arrival at a specific temperature, and hence the current conducted through the PTC thermistor body decreases to automatically control the heat generation of the PTC thermistor body. Accordingly, it is not necessary to attach a temperature-control circuit to the PTC thermistor body, since it operates as a constant temperature-heat generator. The PTC thermistor device can therefore be used as a heat generator for various heat-generating devices, although its structure would have to be modified in accordance with the field of application. When the PTC thermistor device is used for heating compressor oil, the PTC thermistor device must have excellent heat conductivity and heat resistance characteristics.
In addition, the PTC thermistor device must be stable against temperature changes caused by the compression of the compressor oil and also against changes in the ambient atmosphere caused by a leakage of the compressor oil. Furthermore, the PTC thermistor device must be able to resist vibration caused by the compressor.